1. Field of the Invention
The present invention generally relates to the positioning and securement of electrical apparatus. The present invention more particularly relates to a voltage isolation and vibration control device for electrical apparatus including circuit boards installed in a manufactured assembly, such as an electrical cabinet.
2. Description of the Prior Art
Apparatus and methods for positioning, securing and storing electrical components, including circuit boards used for holding electrical components such as capacitors, transformers and resistors, are generally known in the art.
A typical circuit board is provided as a generally rectangular piece of board material which has a surface area suitable for mounting electrical components such as amplifiers, switches, transformers, capacitors, microprocessors and the like. During conventional manufacturing assembly, the circuit board is mounted with a surface area positioned parallel to the back or base surface of an electrical housing, such as a metal electrical cabinet. This parallel orientation of the circuit board can substantially limit available space in the cabinet or enclosure in which the circuit board is installed.
One surface area of the circuit board typically does not have components mounted thereon and is attached directly to the interior of the metal cabinet, such as by insulative spacers which provide an offset distance between the circuit board and the enclosure. The circuit board can be mounted an offset distance of approximately 0.25 inches from the inside surface of the electrical cabinet. This direct mounting, however, can result in damage to the circuit board and its associated components. The mechanical vibrations of rotating equipment, for example, operated adjacent to the electrical cabinet can adversely impact the proper functioning of a directly mounted circuit board.
An electric generator, for example, can generate substantial and detrimental vibrational forces on its own circuitry and electrical components during its operation. With respect to the excitation and control circuitry of the generator, conventional circuit board positioning and securement techniques generally do not sufficiently account for the negative effects of mechanical vibration on the physical structure and electrical operation of the circuit board and its associated components. The rotating shaft of the electric generator produces mechanical vibrations which can cause the generator's excitation and control circuitry to malfunction. In particular, a generator which has been operated over an extended length of time tends to produce more severe mechanical vibrations during its operation, especially near the end of its expected life. In addition, generators which are installed on stationary foundations can be susceptible to vibrations including those caused by earthquakes or other similar seismic events.
Another problem associated with conventional circuit board positioning and securement is how to maintain electrical voltage isolation both between the individual circuit boards and between the circuit boards and the enclosure which contains the circuit boards. An enclosure for circuit boards is typically provided as a metal enclosure. In addition, the use of metal or another electrically conductive material to mount circuit boards directly to a metal electrical housing often does not provide sufficient electrical isolation. This insufficient voltage isolation is of particular concern for potential differences in the range of approximately 2,000 volts sustained on the circuit board.
The use of metal or another suitable material to position and secure circuit boards is also substantially more expensive than the use of plastic materials, for example, such as resinous, molded plastic. Therefore, an additional consideration is that use of metal for either securement or attachment of electrical apparatus such as circuit boards can substantially increase manufacturing and maintenance costs for the apparatus and for the larger system or assembly in which it is employed.
In summary, conventional assembly design for electrical apparatus is deficient in its ability to protect electrical components on circuit boards from the potential threat of damage or failure caused by mechanical vibration. In general, conventional electrical component securement design does not provide a convenient and economical way to establish voltage isolation for components mounted on circuit boards. Conventional electrical devices used for positioning and securement also have not focused sufficiently on economizing available space and avoiding the costs of utilizing expensive resources such as metal and similar materials.